The purpose of this Program Project is to undertake a broadly based interdisciplinary approach to the delineation of the structure of cell surface components. Further, we intend to relate these structural findings to the functional characteristics of cells. The initial major aim will be to apply current methodologies of cell culture, membrane isolation and membrane component purification along with new micro- analytical techniques to elucidate primary structure. The development of microchemical methods will constitute a large portion of this effort. The group examining the structure of these components will be focusing primarily on TL, Thy-1 and H2 antigens from mouse leukemic cell lines and thymocytes. In addition to these detailed structural studies of selected cell surface components, we intend to (1) develop cell surface mutants and define the structural nature of such mutants, (2) examine the mechanism of modulation of cell surface antigens and (3) examine the role of alloantigens in differentiation. Such studies should allow one to understand not only the molecular nature of certain cell surface components, but also their functional properties as a consequence of differentiation or malignant transformation. This understanding should provide clues to events which govern normal as well as abnormal differentiation events.